1. Field of the Invention
The present invention is concerned with a means for transverse cutting of a web of cellular plastic fed continuously out of a forming machine, which means includes a stand-mounted reciprocating carriage moving in synchronism with the web in one direction of traverse and at the same time dividing the web into separate lengths by means of cutting devices.
2. Description of Prior Art
The cellular plastic web consists of porous plastic formed by sintering granules or grains expanded with a blowing agent. Forming machines of the type used for forming in this instance are known. For example, Swedish Pat. No. 171,095 discloses a machine of this type. With continuously operating cellular plastic forming machines it has been the practice for many years to use so-called flying crosscuts equipped with saw blades to cut the continuously moving web into the required lengths. The cellular plastic forming machines first used, which had a comparatively low production rate of aproximately 6m per minute, interacted with cross-cuts based on the principle of a transverse saw blade which was mounted on and moved with a reciprocating carriage to cut the cellular plastic web as the carriage traveled in one direction, and then returned to its starting point.
However, with the further development of cellular plastic forming machines to achieve a production rate approaching 16 to 17m per minute with a web width of 1.0m, the problems of meeting length tolerances with the flying crosscuts increased.
The latest generation of cellular plastic forming machines are capable of a web feed rate of approximately 27m per minute. This has meant an equivalent increase in the demands made on the flying crosscut, but despite very extensive development work the previously used conventional flying crosscut has unfortunately proved unable to meet these increased demands. This is easily understood if we consider that the cutter is required to work under difficult conditions. Given a web traverse of 27m per minute, a cutting length of 1.0m, a web width of 1.25m and a length tolerance of .+-. 2mm, the crosscut has to carry out 27 cuts per minute, including return to a fixed starting point after each cut, direct acceleration from 0 to 27m per minute by the supporting carriage for each cutting operation, and a transverse motion by the saw blade across the 1.25m wide web in a time of not more than 0.8 seconds, starting from a stationary condition.
Under these conditions it has proved both in theory and in practice impossible to do the work using earlier known cutting means.